A long range project intended to solve the theoretical and practical aspects of the problem of attaining layer body section (tomography) in radionuclide scanning of the brain. The accuracy and reliability of brain scintigraphy would be markedly ameliorated by the increased resolution possible by scanning tomography. The prototype of a new device for radioisotope scanning layer body section, the Tomoscanner, is operational and has been tested with radioactive phantoms and in human patients in the Department of Nuclear Medicine of the Case Western Reserve University Hospital in Cleveland, Ohio.